90 Transactions. — Zoology. 



cephala) ; in the North Island the Pied Fantail (Rhipidura 

 flabcllifera) , in the South the Black Fantail (Rhipidura, 

 fuliginosa). The same remark applies to the former of these as 

 to the Saddleback, and the same explanatiom may be offered. 

 It will, perhaps, be objected that this bird is too weak-winged 

 to cross the Straits under any circumstances ; but, as against 

 this, I may mention that during the past twenty years there 

 have been several well- authenticated cases (as recorded in my 

 " Birds of New Zealand ") of the Black Fantail crossing the 

 Straits to the North Island ; and of late years there has not 

 been wanting evidence of its breeding here. What, therefore, 

 is there to prevent such a species becoming naturalized in the 

 North Island, and that without the intervention of any but 

 natural causes'? A gale of wind, under favourable conditions 

 for the passage of the Straits, would alone be sufficient to 

 occasion this dispersal of the species. 



Now, all the representative forms I have named are 

 accepted by ornithologists in general as good and true species. 

 But take any two of them and compare them carefully. "Who 

 can for a moment doubt their common parentage ? — how far 

 back in time, it is not our present purpose to inquire. 

 "Species," "sub-species," and "varieties" are now terms 

 in general use among ornithologists, as well as among other 

 specialists, and, as it seems to me, simply for the purpose of 

 indicating the distinctness or otherwise of the lines of de- 

 marcation separating one from another in their present stages 

 of development under the slow and invisible, but nevertheless 

 inevitable and sure, processes of that law of evolution which go- 

 verns the whole animal kingdom. When we come to study the 

 matter more closely it often seems well-nigh impossible to draw 

 any specific line at all. So-called species often appear to run 

 into one another by insensible gradations ; so much so, indeed, 

 that no two naturalists are agreed as to how much persistent 

 difference is necessary to constitute a species, as distinguished 

 from a sub-species or variety. Take, by way of illustration, 

 the various forms of Woodhen (Ocydromus) inhabiting New 

 Zealand. Dr. Bowdler Sharpe, who, as a rule, does not err 

 on the side of " lumping," has recently declared (Bulletin, 

 1893, p. xxx.), that he finds it impossible to distinguish 

 Ocydromus greyi of the North Island from Ocydromus carli of 

 the South Island. This difficulty arose, no doubt, from the 

 circumstance of his examination of the two forms having been 

 confined to dried specimens. If he had been permitted to- 

 study the live birds he would have seen that, apart from the 

 unmistakable difference in the general hue of the plumage, 

 Ocydromus greyi has brown hides and legs, whereas the 

 southern form (Ocydromus carli) has these soft parts of a 

 lake-red colour. He says further (loc. cit., p. xxix.) that he 



